Wednesday, May 26, 2010

Interval partitioning is an extension of range partitioning which instructs the database to automatically create partitions of a specified interval when data inserted into the table exceeds all of the existing range partitions. You must specify at least one range partition.

You can create single-level interval partitioned tables as well as the following composite partitioned tables:

* Interval-range

* Interval-hash

* Interval-list

Sure, I can create these composite partitions, but the results aren't particularly useful. When I tried. Oracle spread my results nicely between the two hash subpartitions for the manually defined partition, but put everything in the same subpartition for the interval generated partition. Notice that these are identical sets of rows. The only difference is the key to force them into the manually specified partition or the generated partition. I assume that there is a metalink note on this somewhere.

I got equivalent results for interval-list composite partitioning. I won't bore the reader with the step-by-step for that test since the results are also that all rows in the generated partitions are forced into one subpartition.

That's a whole lot of partitions! Clearly that is the maximum possible partitions. It's odd that the developers at Oracle chose to store that value there rather than the actual count of partitions created. They obviously have it available. Ah, the mysteries of the Oracle.

Monday, October 12, 2009

It's Open World! Sunday a full day of IOUG lectures. Today I heard Jonathan Lewis on "Performance Tuning - being an expert"; Greg Rahm on Data Warehousing and Exedata; Cary Millsap on Performance and Chen Shapira on the uses of charts. I had an introduction to desktop widgets from two experts, I was the only attendee. And I had a nice long introduction to Apex at the Demo Grounds.

It is all Wonderful. Just one little question. How am I going to survive 3 more days? I'm going to bed!

Wednesday, September 23, 2009

Today I was sitting in a public library, minding my own business when a man who I had never seen before, leaned over to me and asked me, "Is it true that you can drop and index created explicitly, but not one created implicitly as part of a constraint? Initially the reaction was implicit/explicit? Please speak English. When I sorted that out there were 2 further reactions, also unspoken, "Duh, that's pretty obvious", and "Why me?"

Saturday, August 22, 2009

I see that Oracle Open World Discover ticket costs $50. I remember that it cost something in prior years, but that there was some way to get it for free if you signed up by the early bird date. Is there such a thing again this year?

I have seen the 'chance for a full registration', and have entered, but I haven't seen the free 'discover' pass. Is it around?

OK, I get it, Oracle consults DUAL in the drop process. And don't go messing up a database of any importance. But it is odd how the fact that I was succeeding to mess things up was hidden from me. Yes it told me that I had inserted the row, but then it didn't display it with a select. It was an interesting bit of play.

Saturday, October 18, 2008

The final chapter: The database continued plodding along wretchedly until last Friday night at midnight when I got a call, "The production database is down."I crawled out of bed, bleary eyed, signed in, and tried to start it. I got:

That woke me up. OK, Who/what messed with the control file?I tried to look at the file and got a message that told me that not only was the control file inaccessable, the entire drive /u01 was inaccessable.

I called across the great divide to the company who controls the hardware and eventually got, "The backup battery for the write cache needs replacing in the SAN".

Monday morning I resent my email to management from a week and a half before. I highlighted my paraphrasing of Fitaloon's comment to my first posting on this subject, "Could our problem be caused by the write cache on the disk having some sort of problem? For example, could it be something as simple as failed backup batteries for the write cache?"Thank you, Fitaloon. You hit the nail on the head.

Since the replacement of the battery, our log writer has been zipping right along, good performance, at last!